System and method for reducing gas break out in MPD metering with back pressure

ABSTRACT

A system and method of maintaining back pressure located downstream of the Coriolis meter maintains the pressure downstream of the Coriolis meter in relation to the surface back pressure (SBP). At least one flow control device is located downstream of the Coriolis meter. The flow control device of the present invention (the BPV) automatically maintains the downstream pressure to less than or equal to fifty percent (50%) of the surface back pressure. A pressure regulator sets the back pressure to allow for a standalone device. Additional valves allow adjustment of the back pressure and allow for pressure relief and full flow bypass.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a continuation in part ofU.S. Patent Application No. 62/673,014 filed on May 17, 2019 entitled“SYSTEM AND METHOD FOR REDUCING GAS BREAK OUT IN MPD METERING WITH BACKPRESSURE.”

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not Applicable.

RESERVATION OF RIGHTS

A portion of the disclosure of this patent document contains materialwhich is subject to intellectual property rights such as but not limitedto copyright, trademark, and/or trade dress protection. The owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure as it appears in the Patent and TrademarkOffice patent files or records but otherwise reserves all rightswhatsoever.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to maintaining back pressure downstreamfrom a Coriolis meter. More specifically, the present invention isrelated to a back pressure manifold and a method of managing pressurewithin a managed pressure drilling operation. The present invention isalso related to improving the accuracy of the measurements from theCoriolis meter.

II. Background

In drilling, the Coriolis meter can measure volume flow rates anddensity of the drilling fluid. For example, in a managed pressuredrilling (MPD) system, fluid flow is typically measured using a Coriolisflow meter to determine lost circulation, to detect fluid influxes orkicks, to measure mud density, to monitor fluid returns, etc.

Managed Pressure Drilling (MPD) operations run the risk of gas entrainedin the drilling mud breaking out of solution as the pressure isreleased. In MPD, the gas breaks out of solution after the MPD drillingflow control device, generally, a drilling choke. Some MPD operatorshave resorted to installing a manually operated globe valve downstreamof the Coriolis meter. The MPD operators manipulate this valve to reducethe gas breakout in the meter and to gain metering efficiency with theCoriolis meter.

The installation of such a globe valve has several risks associated withit. Although the globe valve is adjustable, the globe valve is only amanually adjusted fixed orifice. If flow rate is increased, the pressureupstream will also increase. Likewise, if flow rate is reduced, thepressure will drop and Coriolis meter accuracy will once again becomeaffected.

The globe valve provides a fixed orifice. If the globe valve becomesplugged, an overpressure event is possible. The overpressure eventaffects the system and potentially the pressure design operating rangeof components downstream of the MPD flow control device, such as thedrilling choke.

The system and method of maintaining back pressure of the presentinvention provides a significantly better solution and increased systemsafety pressure protection.

SUMMARY OF THE INVENTION

The system and method of maintaining back pressure of the presentinvention provides a back pressure valve manifold system locateddownstream of the Coriolis meter. The back pressure valve manifoldsystem of the present invention provides at least one flow controldevice located downstream of the Coriolis meter.

The at least one flow control device located downstream of the Coriolismeter automatically maintains the downstream pressure to a desiredpressure in relation to the upstream pressure, such as the surface backpressure. The back pressure valve of the present invention (the BPV)automatically maintains the downstream pressure to less than or equal tofifty percent (50%) of the surface back pressure.

During an MPD operation using a fully automated or semi-automated MPDsystem, the MPD control system automatically adjusts a flow controldevice (typically a choke) in order to achieve a desired surface backpressure (SBP). In a pressure system, it is desirable to maintaincritical flow across a pressure drop so that pressure variationdownstream of a flow control device does not affect the upstreampressure, such as the SBP. Critical flow is typically ≤50% of theupstream pressure.

In the present invention, a BPV back pressure valve is locateddownstream of the Coriolis meter. The BPV automatically controls thedownstream pressure in relation to the SBP. As the SBP changes, the BPVadjusts to change the downstream pressure. As the SBP changes in the MPDsystem, the BPV downstream of the Coriolis meter adjusts to be ≤50%(less than or equal to fifty percent) of the upstream pressure (SBP).The adjustment of the downstream pressure minimizes gas breakout ofsolution from the drilling mud. Such adjustments improve the accuracy ofthe flow rate measurement by the Coriolis meter.

It is an object of the present invention to provide a back pressuremanifold system located downstream of the Coriolis meter.

It is also an object of the present invention to maintain the pressuredownstream of the Coriolis meter in relation to the surface backpressure.

It is also an object of the present invention to automatically adjustfor desired SBP set point.

It is also an object of the present invention to automatically adjustthe BPV to maintain back pressure at 50% of the surface back pressure.

It is also an object of the present invention to reduce the flow linevelocity when gas is entrained in solution with drilling mud and drilledcuttings.

It is also an object of the present invention to significantly reducethe potential for erosion at the drilling choke and all downstreamcomponents.

It is also an object of the present invention to set the MPD system witha high maximum pressure to protect the lower pressure rated equipmentdownstream of the MPD choke manifold.

It is also an object of the present invention to provide a fail openbypass actuated valve designed to open in event of either blockage of aCoriolis meter tube(s) or the BPV.

In addition to the features and advantages of the present invention,further advantages thereof will be apparent from the followingdescription in conjunction with the appended drawings.

These and other objects of the invention will become more fully apparentas the description proceeds in the following specification and theattached drawings. These and other objects and advantages of the presentinvention, along with features of novelty appurtenant thereto, willappear or become apparent in the course of the following descriptivesections.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following drawings, which form a part of the specification andwhich are to be construed in conjunction therewith, and in which likereference numerals have been employed throughout wherever possible toindicate like parts in the various views:

FIG. 1 is a schematic view of one embodiment of the present invention;and

FIG. 2 is a partial schematic view thereof.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, the present invention provides a flowcontrol device located downstream from the Coriolis meter 98. Thepresent invention is implemented in a managed pressure drilling system102. The back pressure management system is generally shown as 100. Theback pressure management system 100 is located downstream of the managedpressure drilling system 102 that is located downstream of the RCD 104.

Referring to FIGS. 1 and 2, the back pressure management system 100 isinstalled on a manifold. In one embodiment, a flanged connectionattaches the back pressure management system 100 to the drillingconfiguration.

The back pressure management system 100 provides an inlet 106 downstreamof the Coriolis meter 98 as shown in FIGS. 3 and 4. A pressure regulator108 monitors the pressure. The pressure regulator 108 sets the backpressure. In one embodiment, the pressure regulator 108 sets the backpressure to less than or equal to fifty percent (50%) of the surfaceback pressure.

The pressure regulator 108 provides a simple to use and reasonablyaccurate regulator that sets the back pressure. In one embodiment, thepressure regulator 108 provides a standalone device that is notcontrolled by any external control system. The pressure regulator 108 ofanother embodiment may be controlled by an external control system.

The back pressure management system 100 provides multiple flow controldevices 110, 112 and relief valve 114 to control the flow and pressurethrough the back pressure management system. These flow control devices110, 112 and relief valve 114 maintain back pressure and relievepressure that may exist within the system.

Flow control device 110 may be implemented as a valve. Flow controldevice 110 provides a control valve that handles drilling muds, oil, andwater based drilling muds that carry small particle sized drilledcuttings. Oil and water based drilling muds carry drilled cuttings fromthe wellbore through surface piping and back to the rigs mud handlingsystem. Flow control device 110 applies back pressure to the Coriolismeter to minimize or prevent gas breakout in the Coriolis meter. Theback pressure created by valve 110 improves the accuracy of the meter.

The back pressure management system of one embodiment regulates returnflow to maintain a back pressure. Such an embodiment may not requiresealing shut off. Flow control device 110 of one embodiment properlyhandles pressure control in a range of 0 to 500 psi, more typically100-200 psi.

The actuator must be capable of opening flow control device 110 withfull differential pressure of 1440 psi across the flow control device110. Flow control device 110 should be fail open. The actuator for theflow control device 110 can be electric, pneumatic, or hydraulic. Thevalve position controller 118 adjusts the flow control device 110 to setthe back pressure to be applied by the flow control device on theCoriolis meter.

In one embodiment that receives external control, valve 110 receives apressure control set point from the MPD SCADA (Supervisory Control &Data Acquisition) system as shown in FIG. 1. Logic in the control systemmaintains the set point for pressure control as either ≤50% of the setpressure for the flow control device 120, such as an MPD chokes, up to amaximum set point pressure for valve 110 of 1440 psi (the system'sdesigned working pressure of the downstream choke components).

Flow control device 112 serves as a bypass that avoids flow controldevice 110. To bypass the valve 110, the system opens flow controldevice 112 and closes flow control device 110. Opening valve 112 andclosing valve 110 bypasses the system such that the system does notapply the back pressure through flow control device 110.

The back pressure management system 100 also provides a pressure reliefvalve 114. Relief valve 114 should provide a simple/field pressuresettable. After activation, the relief valve 114 of one embodiment mustbe able to be reset in the field. Relief valve 114 provides pressurerelief and full flow bypass in the event of Coriolis meter blockage orfailure of flow control device 110.

The present invention also provides a method of maintaining backpressure. A pressure regulator monitors the surface back pressure. Themethod sets the back pressure to a percentage of the surface backpressure. In one embodiment, the method enables usage of flow controldevices to control the back pressure. The flow control devices open andclose to set the back pressure to less than or equal to fifty percent ofthe surface back pressure.

From the foregoing, it will be seen that the present invention is onewell adapted to obtain all the ends and objects herein set forth,together with other advantages which are inherent to the structure.

It will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations. This is contemplated by and is within the scope of theclaims.

As many possible embodiments may be made of the invention withoutdeparting from the scope thereof, it is to be understood that all matterherein set forth or shown in the accompanying drawings is to beinterpreted as illustrative and not in a limiting sense.

What is claimed is:
 1. A back pressure system for reducing gas break outof a drilling fluid in a Coriolis meter installed in managed pressuredrilling (MPD) metering with back pressure wherein the drilling fluidflows downstream from the Coriolis meter to the back pressure system,the system comprising: an inlet located downstream of the Coriolismeter; a first flow control device located downstream of the inletwherein the first flow control device applies back pressure on theCoriolis meter; a pressure regulator located downstream of the inletwherein the pressure regulator sets the back pressure applied by thefirst flow control device.
 2. The system of claim 1 further comprising:a second flow control device located downstream of the inlet wherein thesecond flow control device is positioned in parallel to the first flowcontrol device wherein the second flow control device serves as a bypassfor the first flow control device.
 3. The system of claim 2 furthercomprising: a relief valve located downstream of the inlet wherein therelief valve is positioned in parallel to the first flow control deviceand the second flow control device.
 4. The system of claim 3 wherein thepressure regulator sets the back pressure applied by the first flowcontrol device to less than or equal to fifty percent (50%) of a surfaceback pressure upstream of the Coriolis meter.
 5. The system of claim 1further comprising: an actuator that opens and closes the first flowcontrol device.
 6. The system of claim 2 further comprising: aSupervisory Control and Data Acquisition (SCADA) system that sets apressure control set point for the back pressure applied by the firstflow control device.
 7. The system of claim 6 wherein the pressurecontrol set point is set at less than or equal to fifty percent of thepressure of a flow control device of a managed pressured drilling systemlocated upstream of the Coriolis meter.
 8. The system of claim 1 whereinthe first flow control device is a fail open flow control device.
 9. Thesystem of claim 1 wherein the second flow control device closes todirect the drilling fluid to the first flow control device, wherein thefirst flow control device adjusts an opening in the flow control deviceto apply back pressure to the Coriolis meter.
 10. A back pressure systemfor reducing gas break out of a drilling fluid in a Coriolis meterinstalled in managed pressure drilling (MPD) metering with back pressurewherein the drilling fluid flows downstream from the Coriolis meter tothe back pressure system, the system comprising: an inlet locateddownstream of the Coriolis meter; a first flow control device locateddownstream of the inlet wherein the first flow control device controlsback pressure on the Coriolis meter; an opening in the first flowcontrol device wherein the first flow control device adjusts a size ofthe opening to adjust the back pressure applied by the first flowcontrol device to the Coriolis meter; a pressure regulator locateddownstream of the Coriolis meter wherein the pressure regulator sets theback pressure applied by the first flow control device.
 11. The systemof claim 10 further comprising: a second flow control device locateddownstream of the inlet wherein the second flow control device ispositioned in parallel to the first control device wherein the secondflow control device serves as a bypass for drilling fluid to bypass thefirst flow control device.
 12. The system of claim 11 furthercomprising: a relief valve located downstream of the inlet, wherein therelief valve is positioned in parallel to the first flow control deviceand the second flow control device wherein the relief valve providesrelief for the first flow control device.
 13. The system of claim 12wherein the pressure regulator sets the back pressure applied by thefirst flow control device to less than or equal to fifty percent (50%)of a surface back pressure upstream of the Coriolis meter.
 14. Thesystem of claim 12 further comprising: a Supervisory Control and DataAcquisition (SCADA) system that sets a pressure control set point forthe back pressure applied by the first flow control device, wherein thepressure control set point is set at less than or equal to fifty percentof the pressure of a flow control device of a managed pressured drillingsystem located upstream of the Coriolis meter.
 15. The system of claim13 wherein the first flow control device is a fail open flow controldevice.
 16. The system of claim 13 wherein the second flow controldevice closes to direct the drilling fluid to the first flow controldevice, wherein the first flow control device adjusts an opening in theflow control device to apply back pressure to the Coriolis meter. 17.The system of claim 13 wherein the first flow control device closes todirect the drilling fluid through the second flow control device tobypass the first flow control device and avoid applying back pressure tothe Coriolis meter via the first flow control device.
 18. A backpressure system for reducing gas break out of a drilling fluid in aCoriolis meter installed in managed pressure drilling (MPD) meteringwith back pressure wherein the drilling fluid flows downstream from theCoriolis meter to the back pressure system, the system comprising: aninlet located downstream of the Coriolis meter; a first flow controldevice located downstream of the inlet wherein the first flow controldevice applies back pressure on the Coriolis meter; an opening in thefirst flow control device wherein the first flow control adjusts thesize of the opening to adjust the back pressure applied by the firstflow control device to the Coriolis meter; a pressure regulator locateddownstream of the Coriolis meter wherein the pressure regulator sets theback pressure applied by the first flow control device; a second flowcontrol device located downstream of the Coriolis meter wherein thesecond flow control device is positioned in parallel to the firstcontrol device wherein the second flow control device serves as a bypassfor drilling fluid to bypass the first flow control device, wherein thesecond flow control device closes to direct the drilling fluid to thefirst flow control device for the first control device to apply backpressure to the Coriolis meter, wherein the first flow control deviceadjusts an opening in the first flow control device to apply backpressure to the Coriolis meter; wherein the first flow control devicecloses to direct the drilling fluid through the second flow controldevice to bypass the first flow control device to avoid applying backpressure with the first flow control device; and a relief valve locateddownstream of the inlet wherein the relief valve is positioned inparallel to the first flow control device and the second flow controldevice wherein the relief valve provides relief for the first flowcontrol device.
 19. The system of claim 18 wherein the pressureregulator sets the back pressure applied by the first flow controldevice to less than or equal to fifty percent (50%) of a surface backpressure upstream of the Coriolis meter.
 20. The system of claim 18wherein the pressure regulator sets the back pressure applied by thefirst flow control device to less than or equal to fifty percent of thepressure of a flow control device of a managed pressured drilling systemlocated upstream of the Coriolis meter.